The competition is enormous, but with "Pirates of the Caribbean: At World's End," a case could be made for "Pirates" as the worst film series since Thomas Edison got the wacky idea that pictures could move. "Hellraiser," the previous titleholder, looked as though it might hold onto its crown, thanks to its disgusting effects. But the makers of "Pirates" cleverly diminished that advantage with gross undead seamen and lots of rotting teeth. And now it overtakes "Hellraiser" through sheer length and by a novel new effect: The story is so convoluted and impenetrable, so impossible to grasp hold of, that viewers sit there wondering if they've had a stroke.

Cast your mind back to the first "Pirates" movie. That was a little jumbled, too, but it had the spine of a story: A nice guy, Will (Orlando Bloom), is trying to rescue his girlfriend, Elizabeth (Keira Knightley), who has been kidnapped by pirates. (They love each for a good reason -- they're the only two people in the entire 18th century who brush their teeth.) Will hooks up with a pirate captain (Johnny Depp), who acts just like Keith Richards, and they have an adventure.

But "Pirates 3" has no narrative throughline, no emotional spine. It's a mess, and the troubles originated with "Pirates 2." In the last installment, in order to stretch the movie to epic length and guarantee another sequel, the filmmakers introduced new characters and new plotlines, tying themselves into a knot they could not undo by the final credits. "Pirates 3" has inherited that mess, and it's an ugly thing to watch the actors have to pick through it.

Depp as Captain Jack fares the best, because his role is essentially comic. He's never had to carry the story. But Will and Elizabeth, as characters, are destroyed. They've become a mass of multiple motivations and loyalties. Lacking consistency, they're shoehorned into any configuration that the screenwriters devise, to the extent that when we look at them, we no longer see Will and Elizabeth. We see Bloom and Knightley gamely struggling to locate a shred of authenticity in their roles. They don't find it, and it's not their fault. It's not there.

Director Gore Verbinski and his team of writers are almost naive in what they expect an audience to latch on to. At the start of the film, for example, Captain Jack is stuck on an island somewhere. He might never get off. OK, so what? The movie introduces some notion about all the pirate leaders needing to come together or else "the brethren faces extinction." Uh-huh. And what would be so bad about that? The movie's biggest emotional trump card is Will's effort to rescue his father from a death in life (or life in death) aboard a ghost ship. But the movie takes about 45 minutes to reintroduce that story line (from "Pirates 2") and it has little dramatic heft, especially when we meet Dad (Stellan Skarsgard) and see that he's been turned into a kind of monstrous barnacle.

The "Pirates" series had one slender emotional thread on which to hang its story cycle -- Will and Elizabeth's undying, undiminished, idealized romance -- and amazingly, they damaged it, miring it in ambiguity and compromise.

In terms of pure adventure, there's less of it here than in "Pirates 2" -- the action doesn't really start until about two hours in, and even then it's hard to understand the shifting allegiances or make sense of why the different sides are fighting. For most of the screen time, a sour feeling pervades. Everyone seems irritated, with the exception of Geoffrey Rush as Captain Barbossa, who goes through the movie like a man smelling roses while covered in (shall we say) baser substances. His mugging is more subtle than Depp's, but in a way it's funnier, though to talk about performances is a little beside the point. Everyone is hostage to the screenplay. Everyone is on a boat that has already gone off a cliff.

Keith Richards provides the movie's only pure pleasure, with a cameo as Captain Jack's father. The rest of the movie's amusements are unintended. There's the fun, for example, of watching Naomie Harris, as Tia Dalma, make her West Indies accent thicker and thicker and thicker, until she's barely comprehensible, and how she uses the most portentous delivery for dialogue made up almost entirely of non sequiturs. Also diverting, in a sorry sort of way, is the moment in the first scene, when we discover that habeas corpus has been suspended by the evil Lord Cutler (Tom Hollander). Wait. Does that mean if we like habeas corpus, we're supposed to like "Pirates 3," too?

But best of all are Verbinski's repeated long shots of the sailing ship, accompanied invariably by a soaring men's chorus on the soundtrack. Verbinski uses the shots as bridges between scenes, designed to assure audiences that "Pirates 3" has grandeur and continuity. It has neither.

-- Advisory: This film contains violence.

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